Operation of pressure stills



3 Sheets-sheep 1 July 19, 1932. E. c. HERTHEL. y

OPERATION OF PRESSURE STILLS Filed April 21, 1925 July 19, 1932. E. c. HERTHEL OPERATI-ON OF PRESSURE STIILLS Filed April 2l, 1925 3 Sheets-Sheet 2 ATToRNEY July 19, 1932. E. c. HERTHEL.

OPERATION OF PRESSURE STILLS Filed April 2l, 1925 3 Sheets-Sheet 5 INVENTOR fqgene Herf el BY @a M *QM 1 AT1-OR NEYS Patented fJuly 19, '1932 marmo STATES PATENT; oI-l-lclsz- EUGENE c. rpEnrHEI., or onIcAeo, ILLINOIS, As'sIGNon To sINcLAIB BEFINING con-v l PANY, or NEW Yonx, N. Y., A conronA'rIoN or MAINE OPERATION QF PRESSURE STILLS Application Vfiled lApril 21, 1925. Serial No'. 24,734.

, This invention -relates to improvements in pressuredlstlllation processes for cracking Y heavier hydrocarbon oils, such as .gas oil, for

the production of lighter hydrocarbon oils,

such as asolinel and pressure distillate, therefrom., his application is in part a continluation of a prior application'iled January 28, 1922, Serial No'. 532,434.

When hydrocarbon oils are distilled under fpressure at a cracking temperature, they are broken up into lighter oils of less complex molecular structure. In addition to `these -lighter oils, ,the products of the crackingreaction also include carbon, or tar or pitch constituents, and ,fixed gases. In condensing the vapors in the pressure distillatiom the fixed gases escaping from the pressure still with the vapors 'of the cracked oil tend to carry a certain proportion of the condensible components of the vapors with -them through the condenser uncondensed. A.These luncondensed vapors thus associated withthe fixed gases escaping uncondensed from the condenser include particularly the very lightl constituentswhich are desirable components' of motor gasoline. yIf the condensing operation is carried out under pressure, thepro'.- portioriof such vapors-which are condensed may be increased, but, in this case, when the pressure on the condensed distillate is re-l duced to atmospheric pressure the very light constituents again escape as vapors from the condensed distillate." In addition to the gasv mixtures produced in pressure still operation, normal refinery operation is also ac-.i

companied by the production of other. gas mixtures including condensible' constituents suitable as components of gasoline or other commercial oils, such for example' as the gas mixtures produced in coke still operation. Hith rto, it has been the practice to recover such condensible constituents from these various gas mixtures, if at allby separate and additional operations'such `as those employed in the recovery of gasoline `from natural gas and-casing head gas. This invention'includes improvements in the recovery of gasoline constituents fromsuchgas mixtures, rand especially from the gas mixtures produced in pressure distillation or other rcracking procsuch gas mixtures. l 'proportion of the esses;` and includes particularly a cyclic method of operation eliminating such separate and additional o erationsvas have prevlously been employe for the treatment of ewise, a considerable' products of `thecracking d1st1l1at1on is composed of unsaturated hydrocarbons, many of which are/undesirable as components of gasoline and other commercial oils, because of unpleasant odor, ii-y l0 stablhty, etc. Attempts have hitherto been made 'to saturate these undesirable unsaturated constituents by the addition of hydrogen thereto, such as by maintaining thevai porsl from thev 'pressure still Aunder pressure, or by mixing. them with. hydro gen contaimng gases,.but Wit out marked results. This invention also includes yimprovements in the operation of pressure stills whereby such undesirable unsaturated con'- 70 stituents are treated in` the pressure still system to form saturated or. more saturated coms pounds im roving the quality of the pres-4 sure distil ate. The -invention further includes improved methods of operating' res-` sure stills forv controlling the pressure t erein and for promoting the vaporizationv therein ofconstituents suitable .as'com onentsl of the desired 'ressuredistillateg ther feabe apparent as the description'proceeds.

' l Accordingto the present invention, char ing'stock supplied to the ressure stilll 1s first employed" absorbing medium for scrubbinglthe-uncondensed vapors and gases from the pressure still, or other gas mixtures including condensible components suitable as components of the desired pressure distillate, and the absorbed constituents are then distilled fromthe charging stock as it is sup- 00 plied to the pressure stilLsystem, and the absorbed coudensible vapors distilled inthe pressure still system are taken off and condensed withthe vapors forming the pressure distillate.v l The gas mixture supplied to W the scrubbing operation may be that pro: duced in the same or other ressure stills, or the gas'mixtureproduced m other-cracking operations, or other refinery gases including constituents suitable as components 109 may be supplied to the pressure still through a reiuxing operation. One particularly ad .vantageous way 'of carrying out the invention is to' introduce the supply of fresh charging stock containing the constituents absorbed in the 'scrubbing operation .into direct contact with the vapors lfrom ythe pressure still'in a vreflux tower through which -the pressure still vapors pass to the condenser. All or part of the charging stock containing absorbed constituents may thus be introduced into a ,reiuxing operation in accordance with the present invention, or part of the'charging stock may be elsewhere introduced into the pressure still system.

The inventionjwill be Afurther described more particularly in connection with the pressure distillation of gas oil character charging stocksjfor the production of gasoline, or gasoline containing pressure dis-y tillates, but it is intended and will be understood that this further more detailed de-` scription of one way of carryingout the invention is illustrative of the invention and that the invention is not limited thereto. Reference will be made, in connection with this further description of the invention, to the accompanying drawings, which illustrate in a diagrammatic and conventional'manner one type ofv apparatus adapted for carrying out the process of the invention. The pressure still illustrated inthe drawings 1s of the general construction and, operation de` scribed in United States Letters Patent No.

1,285,200 granted `to the Sinclair Refining Company November 19, 1918 on the application of Edward Isom.- The invention is applicable in connection with other pressure l distillation systems, but this particular type of pressure still has been chosen for the purpose of illustration as representing a type of pressure still, and of pressure still'operation, to which the invention is applied "with advantage.

In vthe accompanying Adrawings Figs. 1 and 1A, taken together, represent in elevation and partly in section with parts broken away a pressure still system and as. sociated apparatus adapted for carrying ou the process of the invention,

Fig. 2 represents in elevation and partly in section a modified. arrangement of the condenser andl receiver together with a gas release tower, and t Fig. 3 is a flow sheet illustrating in diagram the process of the invention.

I Referring to Figs. 1 and 1A of the drawings, the pressure still illustrated comprises a bulk supply tank 1 and a battery of heat-v ing tubes 2, the heating tubes being vlocated in the heating flue of a furnace 3 and the bulk supply tank being arranged away from the furnace, and a circulating pump 4 and circulating connections 5, 6 and 7 connecting successively the bulk supply tank, the circulating pump, the lower end of the heating tubes, and the upper end of the heating tubes and the bulk supply tank. Arranged above the bulk supply tank is reflux tower 8 havinga plurality of ba esv 9 therein.- A.

vapor hne 10 is arranged to conduct vapors from the vapor dome 11 on the bulk supply tank to the lower end of the reflux tower and' a reliux return line 12 is arranged to cond'uct reflux, and admixed fresh oil, from the lower end of the reflux tower to the upper end of the circulating connection 5 4on the suction side of the circulating pump 4. i The reflux tower, the bulk supply tank, and the circulating connections may with advantage be insulated against heat loss by the provision of suitable heat'insulating jackets of material such as mineral wool thereon. A connectiony 13is provided for pumping out and charging the still and a tar draw-oli connection 14 is arranged for use during v.the

operation of the still.

Vapors escape from the upper end of the reiux tower 8 vthrough the vapor line 15 to a condenser 16. The condenser discharges through connection 17 into the receiver 18 which is provided with a distillate outlet 19 and a gas outlet 20. The gas outlet from the receiver connects to a header 22 (the gas line being connected at D-D as shown). Gas mixtures from other pressure stills, or from other cracking operations, or other-refinery gases containing condensible hydrocarbon vapors, may be supplied through the header,

21. From this point the gas mixture is conducted to the scrubbing tower through con- 4nection 22. The pressure in the pressure still may be controlled by the regulating valve 23 arranged in the v apor line 15 between the reflux tower and the condenser, or the pressure may `be reduced and regulated beyond the condenser or receiver. :When the receiver is maintained under any substantial pressure,

itis advantageous to employ the arran ement" of apparatus illustrated in Fig. 2. ere

this arrangement of apparatus is employed, A

the vapor line 15 from the reflux tower is connected to a condenser. 24 (the vapor line being connected at E-E as shown) and the gas connection 22 to the scrubbing tower isV connected to the common connection 25 from thel receiver l26and the gas release tower 27 (at F- F as shown). In this modified ar-v rangement of apparatus, the condenser 24 `discharges into the receiver 26 which is provided with a gas release line 28 and a dis! charged. An auxiliary distillate discharge connection 31 is also provided `for use as required. Here the pressure may be reduced and regulated by control valve 32, or the-condenser may be operated under substantially the pressure prevailing in the still and the pressure reduced and regulated beyond the condenser, for example by control valve 33, or the receiver 26 may also be maintained under the pressure prevailing in the still. From the header 30 the condensed distillate is discharged through connection 34 into the gas release tower 27 where the pressure is reduced substantially to atmospheric. Excess gases and vapors absorbed in the distillate under the higher pressure in the receiver or lcondenser are then liberated and escape through connection 35and the distillate free from such constituents is discharged through connection 36V under substantially atmospheric pressure. The vreleased gases and vapors escaping from the receiver through connection 28 and escaping from the 'gas release tower through connection 35 pass together to the scrubbing tower through connection 25.

Again referring to Figs. 1 and 1A, the gas mixture from yconnection 22 is introduced into the lower end of the scrubbing tower 37 through connection 38 and passes upwardly therethrough over baliles or other gas and liquid contact promoting means with which the scrubbing ytower is provided. The stripped gases escape from the upper end `of the scrubbing tower through connection 39 and are discharged into a gas holder 40 through connection 41. A valved by-pass connection 42 is also provided between gas D tower for spraying fresh oil downwardly' line 22 and the gas line 41. vFresh oil is pumped from the charging stock tank 43 by means of pump 44 through connection 45 to the upper end of the scrubbing tower 37 through which it flows downwardly in countercurrent contact with thegases and vapors flowing upwardly therethrough. From the lower end of the scrubbing tow,- er, the oil together with the constituents absorbed therein in thegscrubbing tower is discharged into storage tank 46 through connection 47. A header 48al may connect to this storage tank 46 from which a number of pressure stills may be supplied with fresh oil containing the constituents absorbed in the scrubbing tower. A pump 49 is provided for supplyingfresh oil from this tank to the pressure still system illustrated in Fig. 1. From the'pump 49 one feed oil line 50 leads to the bearings of the circulating pump (the feed line being connected at C-C as shown), and another feed oil line 51 leads to the upper end of the reflux tower l8 (this feed line being connected at B4B as shown). The feed line 51 connects to a spray head 52 arranged in the upper end of the reflux therethrough in direct contactwith the rising vapors from the pressure still. The flow of oil through the feed lines 50 and 51 may be controlled by valves 52 and 53 respectively. Fresh oil may also be supplied to other pressure stills through connection 48 by means of the same pump. The major proportion of fresh oil is supplied to the upper end` of the reflux tower and the minor proportion is introduced throughthe bearings o the circulating pump. The supply of oil introduced into direct contact with the vapors in the reflux' tower is regulated to control the refluxing operation therein, and additional oil required to maintain the still charge is supplied through the bearings of the circulating pump, a minimum suiiicient to cool and protect the bearings of the circulating pump being at all times supplied thereto.

As an illustration of one wayof carrying 'out thepresent invention for the production of gasoline from gas oil in the apparatus il-1 lustrated, the still is charged with 8,000 gals. of gas oil and brought `to cracking condltlons of temperature and pressure in the usual way. After being brought to operating conditions, the introduction of fresh oil into' the reflux tower is begun and the vapors escaping from the reflux tower are condensed and the distillate discharged lthrough the condenser to the receiver. With a gas oil character charge ing stock, pressures in the neighborhood of 90 to 125 lbs. per sq. in. may be employed 1n the still; but the pressure employed may vary, for example, with lighter charging stocks slfch as kerosene character charging stocks still pressures up to 300 lbs. per sq. 1n. or more may be used. However, the pressure on the receiver, or on the gasrelease tower if the receiver is operated at substantially full pressure, may be reduced to atmospheric pressure or to a pressure somewhat above atmospheric but substantially lower than that under which the still is operated, for example suliiciently above atmospheric pressure Ito overcome the frictional resistance of the remainder of the apparatus to the flow of gas or liquid therethrough, and separation -of the distillate and gases is effected at this sub# T s'tantially reduced pressure. Initially, fresh oil is supplied at approximately the rate at which distillate is takenoif, for example with a distillate rate of 1,000 gals. per hr. fresh oil maybe supplied at a rate of about 1,000 gals. per hr. Before the pitch content of the charge reaches saturation, the supply of fresh oil is increased and the withdrawal of tar laden oil from the still cha-rge is begun, the rate of supplyof fresh oil and of withdrawal of ta'r laden oil being regulated. to

maintain the pitch content of the charge below saturation.. For example, wlth a distillate rate of 1,000 gals. per hr. fresh oil may be supplied at a rate of about 2500 gals. per y hour and tar withdrawn at a rate of about Athe desired point for the production of the desired character distillate and the balance of the fresh oil is introduced into vthe circulating charge in the still. By providing a. heat Linsulating jacket on the reflux' tower, a large proportion of the fresh oil may be supplied through the reiiux tower' in direct contact with the vapors therein.

. The charging stock-supplied to the pressure still may, for example, be a gas oil having a gravity in the neighborhood of 28 to B. On its way to the pressure still, this charging stock is passed through the scrubbing tower in countercurrent to the hydrocarbon gas mixture rising therethrough. The relative supply of fresh oil and of gas mixture to the scrubbing operation vary with the amount of gases available, but in normal operation from 150 to 250 gals. of oil per thousand cubic feet of gasmixture will be em ployed. This ratio, however, may vary from somewhat less than 100 to more than 00 gals. per thousand cubic feet of gas mixture. The gas mixture supplied to thel scrubbingoperation' may include .the uncondensed vapors and gases produced in pressure stills in the refinery together with uncondensed vapors and gases from other cracking operations and other hydrocarbonrenery gas mixtures in vvarying proportions. Not only the amount, but also the character of the gases and gas mixtures available in the renery may vary from time to time, for example both the composition and the ambunt of uncondensed vapors and gases may vary at diierent periods in the same pressure distillation operation. These variations tend to be offset by the relatively large amount of oil supplied to the scrubbing operation. In the scrubbing tower approximately20% to 30% of the total gas mixture is absorbed in the oil. Normally, the supply of gas required for pressure still operation is so much in excess of that re uired for absorption that substantially all a sorbable constituents of the gas mixture are removed. With a gas` mixture containing both saturated and unsaturated nconstituents, the gas oil charging stock selectively absorbs the unsaturated constituents, for example, from 60% to -7 5% of the available unsaturated constituents as compared to 15% to 20% or somewhat more of the available saturated constituents. Condensible constituents recovered as such from the gas mixture supplied to the scrubbing operation may amount to as much as 3 to 5 gals. per thousand cubic feet o f gas mixture or more. These condensible con-- stituents are liberated from the fresh charging stock in the pressure still system and are The gas mixture discharged lfrom the pressure still, or pressure stills, either from the receiver or from the receiver and the gas release tower, includes both saturated and unsaturated hydrocarbons together with minor proportions of hydrogen, and sometimes carbon dioxide or carbon monoxide in very small amounts. As a typical analysis, the pressure still gas mixture mayl have a content of unsaturated hydrocarbons of about 31.7% and of saturated hydrocarbons of' about 66.6% by volume; successive absorp- Ition in HzSOg, 80% H2SO4r and finally in fuming sulfuric acid removing the unsat` urated constituents of thisgas mixture successively to the extent of 3.9%, 13.5%, and

13.5%.. Anotherrefinery gas mixture which may be supplied to the scrubbing tower in carrying out the present invention is the mixture of uncondensed vapors and gases from coke still operation. As a typical analysis, such gas mixtures may have a content of about 32.2% of unsaturated hydrocarbons and aboutv 65.7% of saturated hydrocarbons together with minor proportions of hydrogen, and sometimes very small amounts of -f carbon dioxide and carbon monoxide; 70% H2SO4, 80% H2SO4 and fuming sulfuric acid removing successively about 4.8%, 12.2% and 15.4% of the gas mixture. `As a typical analysisof the stripped gases escaping from the scrubbing tdwer, for example, when a mixture containing-'from 50% to 60% of pressure still gases togetherwith coke still gases making up the balance of the foregoing typical analyses is passing through the scrubbing tower, the stripped gas mixture may have a content of unsaturated hydrocarbons of about 14.8% and of saturated hydrocarbons of about 82.3%: 70% H2SO4, 80% HSO; and fuming sulfuric acid removing successively 0.8%, 6.6% and 7.0%. The stripped gas is also substantially reduced in volume as compared to the volume of gas mixture supplied to the scrubbing operation.

The fresh'oil charged with the constituents absorbed in the scrubbing tower is then*` supplied to the pressure still system, and is advantageously supplied to the upper end of the reliux tower in direct contact with the vapors'therein, as illustrated in the drawings and as previously described. As the oil Hows downwardly through the rising vapors of the cracked oil, it is heated by heat given up by the vapors and cools the vapors. The heavler constituents of the vapors are thus refluxed to the stilhb At the same time, the absorbed constituents are liberated in a gradual and progressive manner as the oil Hows downwardly through the reflux tower. The absorbed condensible and non-reacting constituents are thus vaporized and escapeand are condensed with the pressure distillate. The absorbed unsaturated constituents tend to combine with the unsaturated constituents of the vapors forming the pi'essure distillate, and particularly with the less stable and more unsaturated hydrocarbons, ormx ing more stable and more saturated hydro- B', carbons. The unsaturated constituents supplied to the pressure still system absorbed in the/fresh charging stock may be in part condensible and in part incondensible under conditions of practical operation, and part l of these constituents may be condensed as such or part of them may combine with unsaturated constituents of the vapors and gases in the pressure still system, which in turn might be condensible or incondensible under conditions of practicaloperation, to form constituents which are condensed and taken off with the pressure distillate. The unsaturated hydrocarbons absorbed in the fresh oil and supplied to the pressure still system therein do not again appear, but there is an actual decrease in the content of unsaturated hydrocarbons and an vincrease in the content of saturated hydrocarbons of the scrubbing operation. This is illustrated by vthe typical analyses given above.

In the operation of a battery of pressure stills in accordance with the presentl invention in which the gas mixture from the pres- 3 sure stills and the gas mixture from the coke stills in the refinery .were scrubbed in the fresh oil supplied to the pressure stills, the

following average results were obtained over a 42 day period.

l Gas mixture from pressure stills per day:

Cubicl feet 1,696,600 Pounds 1 A120,10()

Gas mixture from pressure stills per barrel 4 charged: e Cubic feet 123. 8-

One of the important advantages of the present invention is that it combines with the CJ pressure still operation the recovery of con'- final stripped gas mixture released from the medium and because of the relatively large owof oil through the scrubbingtower as compared to the flow of gas no particular care and regulation of the relative flow of gas and Voil are' necessary. Moreover, gas

production in a given still corresponds roughly to the rate' of distillation sothat withv high rates of distillation more fresh oil is required compensating for increased gas production. Thel relatively large quantity offresh oil supplied to the pressure stills also avoids anynecessity for a multiplicity of scrubbing towers or recirculation of the absorbing medium. As compared to separate'y oil absorption recovery systems, special still and handling equipment to recover the absorbed `condensible hydrocarbons from the absorbing medium is eliminated, as is `the operation of such apparatus, and there is no necessity for providing special absorbing.

mediums of high initial boiling point to avoid contamination of the recovered light oils. Moreover, as the recoveredlight oils are vaporized in the pressure still system and condensed with the pressure distillate, the

provision of separate storage means is notv necessary; and, as the recovered light oils may be refined with the pressure distillate, special refining operations carried out upon the gas mixture before it is subjected vto absorption treatment, hitherto employed to avoid the high evaporation losses incident tov the refining of the very light oils as recovered in separate operations, .may also eliminated. As illustrated in a diagram matic manner in the flow sheet constituting lFig. 3 of the drawings accompanying this application, in carrying out the' present in'- vention for the production ofgasoline, to

which the present invention is particularly applicable, gasoline constituents suitablev as components of the desired pressure distillate are scrubbed from the gas mixtures in which they occur and a sorbed in fresh charging stock, and the abso d gasoline constituents Vare distilled from the fresh oil as it is supplied to the pressure still vapors produced in the still.

Another important advantage of the present invention is the improvement in vthe qualityeof Ythe vpressure distillates produced in pressure distillation processeswhich it system and are taken off and condensed with the cracked ALao therein.

makes possible. As has been pointed out above, the charging stock to-the pressure still absorbs a large amount of unsaturated constituents from the gas mixture supplied to the scrubbing operation. The heavier more condensible constituents of the gas mixture, for example, may be predominantly unsaturated -in character so that saturated constituents are concentrated in the unabsorbed gases. As the fresh oil 'is heated in the pressure still system, these absorbed unsaturated constituents are liberated within the pressure still system where they tend to combine with unsaturated constituents of the vapors forming the pressure distillate, and particularly with the less stable and more objectionable unsaturated hydrocarbons, forming more stable and more saturated hydrocarbons. In this aspect of the invention, it is particularly advantageous -'to supply to the scrubbing operation gas mixtures containing a considerable proportion of unsaturated components, such as the gas mixture produced in' pressure distillation. processes or in other cracking processes.

The present invention has several further additional advantages when carried out in connection with pressure distillation processes in which the vapors are subjected to a reiluxing operation and when the fresh oil containing absorbed constituents recovered in the scrubbing operation -is supplied to the reflux-,

ing operation in direct contact with the vapors Bg' carrying out the operation in this way, a sorbed condensible constituents,

suchv as uncondensed asoline constituents,

are liberated from the resh oilin the reiiuxing operation by the heat given up by the va ors and these vaporized constituents pass o from the reiuxing operation together with the vapors of the cracked oil Without being subjected to the higher temperature prevailing in the pressure still proper. Likewise, in such operations, absorbed unsaturated constituents areprogressively liberated from the fresh oil as it is heatedup by contact with the vapors in the refluxing operation and are thus intermingled with the vapors of the cracked oil in a particularly advantageous way and at a temperature which apparently promotes the combination of the various unsaturated com onents of the` rating operation with tion is that it provides an improved method -of controlling -the pressure in the pressure still operation. In addition to the condensible constituents and the reacting unsaturated constituents which are absorbed in the fresh oil supplied to the pressure distillation in accordance with the present invention, a certain amount of saturated fixed gases are absorbed as well as a certain amount of unsaturated ixed gases which may not react,

and these latter gases are liberated from the chargedfresh oil as it is supplied to the pressure still system, assisting in maintaining the pressure therein and providing a readily controlled partial pressure of fixed gases in the pressure still by reason of which vaporizaabsorbed fixed vases introduced with the'v fresh oil are quietly and progressively released in the reiluxing operation withou't disturbing the oil in the pressure still proper and there is no tendency for the liberated gases in escapingto entrain heavier oil constituents as in the case where fixed gases arek introduced beneath the surface of the liquid 95 charge in a pressure still. In this way, the pressure still may be continuously kept charged with a fresh supply of fixed gases suiiicient to maintain the desired pressure on the system.

)I claim:

1. In the pressure distillation of heavier hydrocarbonoils for the production of lighter hydrocarbon oils, subjecting the heavier oil to a cracking temperature and'taking olf under pressure the gase and vapor mixture generated thereby, subjecting the gas and 44vapor mixture uto a condensing operation,

separating condensed distillate from the remaining uncondensed vapors and gases at a pressure substantially lower than that atl which the gas and vapor mixture is taken off from the cracking operation, scrubbing uncondensed vapors and gases from the separesh heavier oil and introducing the heavier oil containing the constituents absorbed from the vapors and gases therein directly into the hot gas -and vapor` mixture generated in the cracking operation, separately discharging unabsorbed gases from the scrubbing operation and taking olf together absorbed constituents liberated from the fresh heavier oil and the vapors of the cracked oil without again subjecting them to the cracking temperature.

2. In vthe pressure distillation of heavier hydrocarbon oils for the production of light vhydrocarbon oils, subjectlng the heavier oil to acracking temperature and taking olf under pressure the gas and vapor mixture gentaining condensible scrubbing operation into the refluxing opera-- tion in direct contact with the gas and vapor mixture therein, separately discharging unabsorbed gases from the scrubbingl operation and returning reflux together with admixed unvaporized fresh oil constituents from the refluxing operation to the cracking operation.

3. In the pressure distillation of heavier hydrocarbon oils for the production of lighter hydrocarbon oils, subjecting the heavier oil to a cracking temperature and taking olf under pressure the gas and vapor mixture ,l

generated thereby, subjecting the gas and vapor mixture to a condensing operation, separating the remaining uncondensed vapors and gases from the distillate'formed by the condensing operation ata pressure substantially lower than that at which the gas and vapor mixture is taken ofi1 from the cracking operation, scrubbing .with fresh heavier oil a hydrocarbon gas mixture including uncondensed gases separated from the cracked gas and vapor mixture and c onhydrocarbon constituents, introducing the heavier oil with the constituents absorbed from the gas mixture .directly into the hot cracked gas and vapor mixture generated in the cracking operation, separately discharging unabsorbed gases from the scrubbing operation and taking off together absorbed condensible constituents liberated from the fresh heavier oil and the vapors of the cracked oil without again subjecting them to a cracking temperature.

4. In the pressure distillation of heavier hydrocarbon oils for the production of light hydrocarbon oils, subjecting the heavier oil toa cracking temperature and taking off under pressure the gas and vapor mixture generated thereby, subjecting the gas and vapor mixture successively to a refluxing and to a condensing operation, separating the remaining uncondensed vapors and gases from distillate formed by the condensmg operation at a pressure substantially lower than that at which the gas and vapor mixture is taken olf from the crac 'ng operation, scrubbmg with fresh heavier oil an hydrocarbon gas mixture containingcondensible hydrocarbon constituents, saidv gas mixture including gases separated from the distillate in the separating operation, introducing the heavier voil with constituents absorbed from the gas mixture in the/scrubbing operation into the retluxing operation in direct contact with the gas and vapor vmixture therein, separately discharging unabsorbed gases from the scrubbing operation and returning reflux and admixed unvaporized fresh oil constituents from the reliuxing operation to the cracking operation.

5. In the pressure distillation of heavier hydrocarbon oils for the production of light hydrocarbon oils, subjecting the heavier oil to a cracking temperature and' taking off under pressure the gas and vapor mixture generatedthereby, subjecting the gas and vapor mixture successively to a refiuxing operationv and to a condensing operation, separating remaining uncondensed vapors and gases r distillate formed by the condensing operation at a pressure substantially lower than that at which the gas and vapor mixture is taken olli' from the cracking operation, scrubbing with fresh heavier oil an hydrocarbon gas mixture including uncondensed gases separated from the distillate in the separating operation and containing saturated and -unsaturated hydrocarbon constituents whereby the unsaturated constituents are selectively absorbed in the heavier oil, introducing the heavier oil with constituents absorbed from the gas mixture into the refluxing operation in direct contact with the gas and vapor mixture therein, separately discharging unabsorbed gases from the scrubbing'operation and returning reflux and admixed unvaporized fresh oil constituents from the refiuxing operation to the cracking operation.

In testimony whereof I affix mv signature EUGENE C. HER'IHEL.

' lso 

